Guide to Solar Panels and Central Heating

Most people associate solar power with running electrical appliances and everyday items around the home.

But more and more often solar is being used for heating, especially as the electrification of this area becomes increasingly more widespread. 

Electric-based heating is largely being used to replace gas. Traditionally, ‘central heating’ in the UK is associated with a gas-based system that uses a combi boiler to heat water, which circulates its way through radiators around the home to provide warmth.

Statistics from 2023 show that over 80% of UK households use combi boilers for heating, with around 78% relying on gas central heating. 

These are huge percentages, but we are expecting them to reduce in the coming years to allow the government to meet net zero targets. There were proposals to ban gas boilers in all new builds from 2025 under the Future Homes Standards but we’re still waiting on the details.

All of this means that solar-powered central heating systems are in the spotlight. Government initiatives like ECO4, the Home Upgrade Grant and VAT reductions on energy-efficient installations are helping make solar heating more accessible. 

The post will take a good look at how solar panels can complement central heating systems, the options out there and key considerations to bear in mind.

Can solar panels work with water-based central heating systems?

Yes, solar panels can work with water-based central heating systems. However, they’re not the standard solar panels you’re probably used to. 

Solar panels that work with water-based systems are called solar thermal panels. They can also be known as solar collectors. Unlike photovoltaic (PV) panels which generate electricity, solar thermal panels are designed specifically to heat water. 

Just like their PV cousins, solar thermal panels are usually mounted on a south-facing roof where they absorb sunlight. These special panels contain tubes that are filled with a type of fluid that can absorb this solar energy. The heated fluid gets circulated to a solar-compatible hot water cylinder in the home, where it can be used for domestic hot water needs or, in some cases, to support central heating. 

Like PV panels, solar thermal panels work much more efficiently during the summer months. This means a backup heating source, usually via a boiler or solar immersion heater, is often necessary when winter kicks in. 

Are solar thermal panels compatible with gas combi boilers?

Yes and no. 

Not all combi boilers are compatible with thermal energy systems. This usually comes down to whether the boiler can accept pre-heated water. If it doesn’t, then you’ll be struggling to make these two systems work together. This is one to check with the boiler manufacturer. 

When combi boilers are compatible with solar thermal panels, and they can accept pre-heated water, you can effectively lower gas consumption as you don’t need as much to heat the water. 

Costs of solar thermal systems

Investing in a solar thermal system will cost you between £3,000 and £7,000. The precise price depends on the size and efficiency of the solar collectors used. 

Higher-quality solar collectors often come with a premium but offer better performance and longevity. You may need additional kit, such as a thermal storage tank to keep hot water for longer, which can add to the total price. Installation complexity, as well as any necessary roof adjustments, may also affect overall costs. 

These costs can be a little too much for many homeowners, mainly because they don’t give you a complete solution – you’ll still need to have a secondary option such as a boiler or immersion heater for use during the winter. 

How do solar photovoltaic panels work with heating systems?

Combining solar energy with a gas combi boiler has its difficulties and drawbacks. This is mainly because gas heating isn’t easily paired up with solar-generated electricity. It’s possible but there are more systems and mediums at play. It’s not that simple to link up electricity, water and gas. 

However, pairing solar PV panels that generate electricity with electric heating systems is much more straightforward. The only conversion that needs to be made here is switching the electricity from DC to AC. 

There are now a range of electric heating options available. These can technically power everything from electric boilers to underfloor heating systems. The main issue is whether solar panels can generate enough energy across the year to cover the cost of running a central heating system on a regular basis.

If not, then the high unit cost of electricity from the national grid can make these systems more expensive than the gas equivalents.

Electric heating options compatible with solar PV

Electric boilers

Electric boilers work the same way as gas boilers in that they heat water for your radiators, taps and showers – the key difference is that they rely solely on electricity. When paired with a PV solar system, an electric boiler can run on your own renewable energy, reducing reliance on the grid and decreasing your carbon footprint. 

Electric boilers are compact and often easier to install than gas systems as they don’t require flues or gas lines. This option is good for households looking to move away from gas entirely and who have smaller hot water demands. However, because electric boilers can use a significant amount of electricity, pairing them with solar PV and possibly a battery storage system can help offset energy costs during peak heating times.

Heat pumps

Heat pumps are a highly efficient electric heating option that transfers heat from outside (air-source) or from the ground (ground-source) into your home. Rather than generating heat, they concentrate and move it, using far less electricity than standard electric heaters or boilers. You can think of them as a fridge in reverse. 

Heat pumps work well with solar PV as the electricity generated can power the pump during the day. Heat pumps have no problem operating in the winter and will still produce heat in sub-zero weather. However, solar panels have a much reduced energy generation during the darker winter months and it probably won’t be possible to run the heat pump on solar power alone. 

Hybrid systems

A hybrid system combines a heat pump with a traditional boiler (often gas). For the homeowner they offer the best of both worlds, but still unfortunately rely on gas. That said, they could be a good stepping stone into a fully renewable energy system. 

Essentially a hybrid system uses energy prices and outside temperature to choose the most efficient energy source at the time to meet the energy demands of your home. This requires the installation of a smart control system. Hot water needs are sourced immediately via the gas boiler. 

By pairing with solar PV, the heat pump part of the system can run on renewable energy when solar is available. This setup reduces overall gas consumption and provides reliable warmth in all seasons.

Electric radiators and infrared panels

Electric radiators and infrared panels are versatile, room-specific heating solutions. Electric radiators act like traditional radiators, but use electricity rather than gas-powered hot water. 

Although fully electric, infrared panels provide a different form of heating. They provide radiant heat, which warms objects and people directly. Infrared panels don’t warm air particles that circulate around the room, but the air will warm slowly over time as heat re-radiates out from objects and people. 

Both of these low maintenance systems are good for targeted heating, allowing you to only heat the rooms you’re using. As they work almost instantly, you don’t have to keep these systems turned on. This zoned heating approach is energy-efficient and can help reduce costs by avoiding unnecessary heating throughout the home. Read more on are infrared panels more efficient that standard radiators.

It does mean that your home will feel different compared to a traditional gas-based central heating radiator system. 

Electric underfloor heating

Underfloor heating offers comfortable, consistent warmth and works especially well with PV solar systems. 

Electric underfloor heating is often installed in bathrooms, kitchens or entire ground floors, providing radiant heat from below that warms the entire room evenly. Because underfloor heating can be energy-intensive, pairing it with a PV system helps reduce running costs. This is especially true when used in combination with a battery to store excess solar energy. 

The slow release of heat from underfloor systems means rooms stay warmer for longer, even after the power is turned off, making it a highly efficient choice. With smart thermostats, you can schedule heating to turn on during sunlight hours to make the most of your solar power.

The benefit of battery storage and smart control systems

Battery storage and smart controls can increase the efficiency of solar-powered heating. 

A solar battery storage system can capture excess solar energy for use during evening hours, overcast days or even save for early morning use. They essentially extend the availability of your self-generated solar power, which is the cheapest form of energy you can get. Storing solar power during peak sunlight and using it in the evenings helps reduce reliance on the grid, allowing you to shift your consumption to off-peak times.

Smart thermostats and control systems allow you to optimise your heating times, scheduling usage for when solar production is highest. They’re all about increasing the efficiency of your energy use and systems to reduce running costs. 

Costs of solar PV panels for central heating

The cost of a solar panel system large enough to support central heating can vary widely. At the lower end you can expect to pay at least £4,500 for a 3kW system. However, this is unlikely to be able to provide enough power for a central heating system. 

On the larger end, you can pay up to £12,000 for a more extensive 10kW solar array. With this size being able to produce 40kW of electricity on a good, sunny day, you can certainly power a central heating system with it. 

Any solar panel prices you get should include all essential components, such as the PV panels, inverters and the complete installation process. Despite the upfront investment, a solar PV system with enough power to run your heating will provide you with significant long-term savings.

Benefits of combining solar panels with central heating

The integration of solar panels with central heating systems can offer plenty of lasting benefits. Here are some of the main advantages:

• Financial savings – Solar-powered heating systems reduce both electricity and gas expenses, gradually offsetting the upfront installation costs. By generating your own renewable energy, you can cut monthly heating bills considerably, making solar a cost-effective long-term investment.
• Carbon reduction – Using renewable solar energy instead of fossil fuels greatly reduces carbon emissions. Unlike some greener tariffs, you know exactly where your energy has come from when using solar! 
• Increased property value – Homes with solar panels are increasingly appealing to potential buyers who value both sustainability and the cost saving measures they bring. Many buyers are drawn to properties that promise lower utility bills and are less reliant on non-renewable energy sources. Solar panels can add 4-14% to a home’s price. 
• Protection against energy price rises – With solar, homeowners are less affected by rising energy prices. This provides a buffer against sharp market price increases that we’ve seen in recent years. This greater control over energy costs offers financial stability and peace of mind.
• Low maintenance – Solar systems are designed to be durable and low-maintenance, with most installations requiring only periodic cleaning and occasional system checks. Once installed, solar panels have a lifespan of 25-30 years – even after this they can still be producing energy. Solar offers reliable performance with minimal upkeep.

Can solar panels and central heating work together?

There are many different options at play here, making a definitive answer difficult to propose. 

It’s clear that solar energy can be a powerful tool to support various electric heating systems. However, pairing solar panels with traditional gas central heating has its limitations. That said, they can work together with an extra system or two to make them compatible. It becomes more difficult when using solar to heat water, but it can be done.

The cost-effectiveness of using solar to power heating depends on several factors, including the efficiency and size of the heating system, the solar panel array and local conditions. Each home is unique, so consulting with a professional installer is the best way to determine the right setup for your needs.